ON THE two occasions in my life when I have been stopped and searched I was left feeling more baffled than angry.

On the first I was stopped in a park by police who said they were investigating the theft of plants. Given that I was in shirt sleeves and wasn't carrying anything it was puzzling to see how I could have been making off with a bunch of begonias.

On the second occasion at Gatwick Airport I was handed a slip of paper giving the reason for being searched as "going near equipment". As far as I recall I hadn't been anywhere other than Sock Shop. Is there a secret piece of security equipment nestling among the socks?

Admittedly, if I were black, lived in South London and felt I was being searched frequently purely on account of my colour, I might take a different view. There are plenty of stories of over-zealousness on the part of police officers. Even so, does sending immigration officials to conduct spot checks outside a Tube station really turn us into "Nazi Germany", as one bystander complained?

Nazi Germany, as we all know, was a criminal regime which murdered millions of people. The Border Agency guards sent to conduct spot checks in several London boroughs this week, on the other hand, are simply using a novel technique to try to catch a few more of the 863,000 illegal immigrants which a European Commission study last year estimated to be living in Britain.

Most people - and all the main political parties - agree that we need immigration laws to prevent overcrowding and the collapse of public services. And if we are going to have immigration laws we need to allow officials to enforce them - without automatically accusing them of being instruments of a fascist state.

Such is the fury that the Equality and Human Rights Commission is to launch an inquiry into stop and check but you can’t catch illegal immigrants by staying in offices.

People who are working illegally, are not paying any taxes, are living in illegally sub-let flats and are not signed on with NHS doctors operate beneath the radar of officialdom. They are only ever going to be caught if they commit an offence which brings them to the attention of the police – or if they are intercepted by officials sent out on to the streets to look for them.

None of this is an excuse for being rude and overbearing. Border Agency guards conducting checks should never be anything other than polite. If they are not they will irritate the people they are questioning and make their own jobs far more difficult.

Why shouldn't we also accept that we might be stopped if we are travelling on the Tube or are in an area which has a serious crime problem?

But people who oppose these powers on principle need to ask themselves whom they are protecting. Like it or loathe it, the closely related stop and search policy has had dramatic effects, not least on London knife crime.

In 2008, 22 teenagers were stabbed to death on London's streets. The following year the toll more than halved. Why? Because in the meantime the Metropolitan Police had launched Operation Blunt, which involved stopping and searching 24,000 young people every month. Many of them I suspect hated the experience, not least the 10,200 people who were arrested as a result. But the operation allowed the police to win the streets back from gangs who had come to regard them as their own.

We take it for granted that when we catch a plane or attend a sporting fixture that we will have our bags searched. So why shouldn't we also accept that we might be stopped if we are travelling on the Tube or are in an area which has a serious crime problem? And yes, if we are in an area which has large numbers of illegal immigrants why shouldn't we accept we might be stopped and asked whether we have the right to live in Britain? I don't want to dismiss the claims of people who complained about this week's Border Agency checks being "racist and intimidatory". Border Agency guards should not single out everyone who is non-white.

Besides anything else it would be a poor way of targeting illegal immigrants when 12 per cent of British citizens fall into this category and when many illegal immigrants come from largely white countries. If someone believes they have been subjected to intimidatory tactics they should be heard and, if they are found to have a case, the Border Agency staff concerned should be disciplined or sacked.

Stop and search operations depend on public consent. This can be won if the police, Border Agency guards or whoever else is conducting them explains why they are necessary. The searches should be proportional to the problem they have been set up to solve. Police should never, for example, set up a road block to search for terrorists - and then use it as an opportunity to swoop on motorists with out-of-date tax discs. But many who rise up in fury every time they hear the words "stop and search" are not motivated by reasonable concerns.

They have a problem with authority and will always side with people who find themselves on the wrong side of the law. It is the same liberal mentality which wants prison inmates released en masse. For years our immigration system has been a joke. While our laws are notionally tough, in practice the efforts to remove people who have no right to be here have been half-hearted. We should welcome the sign that Border Agency staff are determined finally to get on top of the problem.